documentation/poky-ref-manual/technical-details.xml: new x32 section added.
(From yocto-docs rev: 78f8b0367b3e5bbc71712f71fe87367d929424c8) Signed-off-by: Scott Rifenbark <scott.m.rifenbark@intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
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Scott Rifenbark
Richard Purdie
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@ -566,6 +566,119 @@
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</section>
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</section>
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<section id='x32'>
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<title>x32</title>
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<para>
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x32 is a new processor-specific Application Binary Interface (psABI) for x86_64.
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An ABI defines the calling conventions between functions in a processing environment.
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The interface determines what registers are used and what the sizes are for various C data types.
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</para>
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<para>
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Some processing environments prefer using 32-bit applications even when running
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on Intel 64-bit platforms.
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Consider the i386 psABI, which is a very old 32-bit ABI for Intel 64-bit platforms.
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The i386 psABI does not provide efficient use and access of the Intel 64-bit processor resources,
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leaving the system underutilized.
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Now consider the x86_64 psABI.
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This ABI is newer and uses 64-bits for data sizes and program pointers.
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The extra bits increase the footprint size of the programs, libraries, memory, and file system size
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requirements.
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Executing under the x32 psABI enables user programs to utilize CPU and system resources
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more efficiently while keeping the memory footprint of the applications low.
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Extra bits are used for registers but not for addressing mechanisms.
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</para>
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<section id='support'>
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<title>Support</title>
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<para>
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While the x32 psABI is not fully implemented with this release of the Yocto Project,
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it is partially functional.
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As of this release of the Yocto Project, x32 psABI support exists as follows:
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<itemizedlist>
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<listitem><para>You can create packages and images using an x32 psABI on x86_64 architecture targets.
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</para></listitem>
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<listitem><para>You can use the x32 psABI support through the <filename>meta-x32</filename>
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layer on top of the OE-core/Yocto layer.</para></listitem>
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<listitem><para>You can use the toolchain for building x32 psABI program binaries and kernel support
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from the <filename>experimental/meta-x32</filename> layer.</para></listitem>
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<listitem><para>You can successfully build many recipes with the x32 toolchain.</para></listitem>
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<listitem><para>You can create and boot <filename>core-image-minimal</filename> and
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<filename>core-image-sato</filename> images.</para></listitem>
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</itemizedlist>
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</para>
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</section>
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<section id='future-development-and-limitations'>
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<title>Future Development and Limitations</title>
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<para>
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For this release of the Yocto Project, the x32 psABI kernel and library interfaces
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and their use are not finalized.
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</para>
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<para>
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Plans for the x32 psABI in the Yocto Project include the following:
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<itemizedlist>
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<listitem><para>Enhance and fix recipes so they fully
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support x32 toolchains and binaries.</para></listitem>
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<listitem><para>Complete RPM Package Manager (RPM) support for x32 binaries.</para></listitem>
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<listitem><para>Support larger images.</para></listitem>
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<listitem><para>Integrate x32 toolchain and kernel changes from
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<filename>experimental/meta-x32</filename> into OE-core.</para></listitem>
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</itemizedlist>
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</para>
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</section>
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<section id='using-x32-right-now'>
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<title>Using x32 Right Now</title>
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<para>
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Despite the fact that the x32 psABI is incomplete for this release of the Yocto Project, you can
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use it to some degree.
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Follow these steps to use the x32 spABI:
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<itemizedlist>
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<listitem><para>Add the <filename>experimental/meta-x32</filename> layer to your local
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<ulink url='&YOCTO_DOCS_DEV_URL;#yocto-project-files'>Yocto Project Files</ulink>
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Git repository.
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You can find the <filename>experimental/meta-x32</filename> source repository at
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<ulink url='&YOCTO_GIT_URL;'></ulink>.</para></listitem>
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<listitem><para>Edit your <filename>conf/bblayers.conf</filename> file so that it includes
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the <filename>experimental/meta-x32</filename>.
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Here is an example:
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<literallayout class='monospaced'>
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BBLAYERS ?= " \
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/home/nitin/prj/poky.git/meta \
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/home/nitin/prj/poky.git/meta-yocto \
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/home/nitin/prj/meta-x32.git \
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"
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</literallayout></para></listitem>
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<listitem><para>Enable the x32 psABI tuning file for <filename>x86_64</filename>
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machines by editing the <filename>conf/local.conf</filename> as follows:
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<literallayout class='monospaced'>
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MACHINE = "qemux86-64"
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DEFAULTTUNE = "x86-64-x32"
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baselib = "${@d.getVar('BASE_LIB_tune-' + (d.getVar('DEFAULTTUNE', True) \
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or 'INVALID'), True) or 'lib'}"
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#MACHINE = "atom-pc"
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#DEFAULTTUNE = "core2-64-x32"
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</literallayout></para></listitem>
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<listitem><para>Use BitBake to build an image that supports the x32 psABI.
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Here is an example:
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<literallayout class='monospaced'>
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$ bitake core-image-sato
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</literallayout></para></listitem>
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<listitem><para>Run your image using QUEM:
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<literallayout class='monospaced'>
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$ runqemu qemux86-64 core-image-sato
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</literallayout></para></listitem>
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</itemizedlist>
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</para>
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</section>
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</section>
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<section id="licenses">
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<title>Licenses</title>
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